Many different production processes that involve high temperature conditions are commonly used in a wide range of chemical industry fields. The leakage of liquids and gases from the pipe joints in these production lines is prevented by gaskets, welding, and so forth. Up to now, gaskets with excellent flexibility have been made from organic polymer materials, for example. Unfortunately, these materials do not have high heat resistance, with the highest being about 350° C. with an imide resin, so metal gaskets have to be used at higher temperatures, but a problem is that these metal gaskets are not as flexible as those made from organic polymer materials.
Aluminum foils and vapor deposited aluminum films do offer high gas barrier performance, but they are not transparent. Also, since an aluminum foil is a metal, it cannot be used as a sealing material to be wrapped around a threaded component. Vapor deposited silica films are transparent and have excellent gas barrier performance, but because the material that serves as a base in these vapor deposited silica films is an organic compound film, once again these films cannot be used under high temperature conditions over 350° C. In addition to being used as gaskets, these gas blocking materials are sometimes used by being wrapped around joint threads, wrapped around a tube, or stuck onto a flat member.
Enzymes such as glucose oxidase are generally useful as biocatalysts, have extremely high selectivity, and have the characteristic of specifically conducting a reaction, but a drawback is their poor heat resistance. However, it is known that the thermal stability of organic materials is generally quite high when they are enclosed in an inorganic material. In view of this, there have been a number of attempts at improving the thermal stability of these enzymes by enclosing them in an inorganic material, for example.
Nylon resins are widely used as molding materials because of their excellent strength and wear resistance, but they also have a low thermal deformation temperature, have poor dimensional stability after absorbing moisture, and shrink considerably in molding, among other drawbacks. Therefore, there has been research into adding clay as a filler in an effort to raise the thermal deformation temperature, increase dimensional stability during moisture absorption, and reduce molding shrinkage. One nylon resin composition that has been proposed contains a mixture of 35 to 80 wt % nylon resin, 20 to 65 wt % of one or more fillers selected from among talc, calcium metasilicate, calcined clay, and silica, and 1 to 10 wt % glass fiber, with this mixture being pelletized in an extruder (Japanese Laid-Open Patent Application S51-7056). In this case, however, a problem is that it is difficult to blend the nylon resin with the filler and glass fiber if the nylon resin accounts for less than 35 wt %.
A method that has been developed for manufacturing a clay mineral and nylon composite with excellent rigidity and impact resistance involves using a fibrous clay mineral such as sepiolite or palygorskite in a proportion of 1 to 30 weight parts (as solids) per 100 weight parts of nylon monomer (Japanese Patent Publication H6-84435). In this case, however, a problem is that if the amount of fibrous clay mineral is over 30 weight parts, there is less contact between the nylon monomer particles, and the molecular weight of the nylon is lower. These methods were mainly developed with an eye to enhancing the characteristics of nylon, and the proportion of the total weight of the material accounted for by the clay mineral is 65% or less.
Meanwhile, clay thin films have been produced up to now using the Langmuir-Blodgett method (H. Shiramizu, “Clay Mineralogy—Basics of Clay Science,” Asakura Shoten, p. 57 (1988)). However, this method involved forming a clay thin film on the surface of a substrate made from glass or another such material, and a clay thin film that was strong enough to be self-supporting could not be obtained. There have also been reports of various methods for preparing functional clay thin films and the like. For instance, there is a method for manufacturing a clay thin film in which an aqueous dispersion of a hydrotalcite-based interlayer compound is made into a thin film and dried (Japanese Laid-Open Patent Application H6-95290), a method for manufacturing a laminar clay mineral thin film in which the bond structure of a laminar clay mineral is oriented and fixed by performing a heat treatment that promotes a reaction between the laminar clay mineral and phosphoric acid or phosphoric acid groups (Japanese Laid-Open Patent Application H5-254824), and an aqueous composition for a coating treatment, containing a complex compound of a divalent or higher metal and a smectite-based clay mineral (Japanese Laid-Open Patent Application 2002-30255), to name just a few of the many extant examples. Nevertheless, there are no cases of the development of a clay oriented thin film that has enough mechanical strength to be used as a self-supporting film, and in which layers of clay particles is highly oriented.
Also, it is known that a film with uniform particle orientation can be formed by dispersing clay in water or an alcohol, spreading out this dispersion over a glass sheet, and leaving it to dry, and oriented samples for use in X-ray analysis have been prepared (Y. Umezawa, Nendo Kagaku, Vol. 42, No. 4, 218-222 (2003)). However, when a film is formed on a glass sheet, it is difficult to peel the clay film away from the glass because cracks develop in the film during peeling, for example, so it has been difficult to obtain a self-supporting film. Also, even if the film can be peeled off, the resulting film is brittle and lacking in strength, and there has been no method for preparing a film that is uniform in thickness and free of pinholes. Accordingly, clay thin films have not as yet been applied as self-supporting films.
Also, polymers that are soluble in water are used as molding materials, and are also added as a dispersant, thickener, or binder to an inorganic material and used as a gas barrier material. For instance, a composition is formed from 1 to 10 weight parts of a clay mineral or other inorganic laminar compound and 100 weight parts of a mixture of (A) a highly hydrogen-bondable resin containing two or more carboxyl groups per molecule and (B) a highly hydrogen-bondable resin containing two or more hydroxyl groups in its molecular chain, where the weight ratio A/B=80/20 to 60/40, molding a film with a thickness of 0.1 to 50 μm from this composition, and subjected this film to heat treatment and electron beam treatment, the result of which is that this film has gas barrier properties (Japanese Laid-Open Patent Application H10-231434). In this case, however, a problem is that the main component is a water-soluble polymer resin, so heat resistance is not very high.
Also, a laminated film that has excellent moisture resistance and gas barrier property and is suited to food packaging can be obtained by laminating a layer composed of a resin composition containing a resin and an inorganic laminar compound between two polyolefin-based resin layers (Japanese Laid-Open Patent Application H7-251489). In this case, however, the layer of resin composition containing an inorganic laminar compound is used as part of a multilayer film, and not alone as a self-supporting film. Also, the volumetric ratio of this resin composition (an inorganic laminar compound/resin) is specified as being between 5/95 and 90/10, with the resin contained in an amount of at least 10%.
So far there has been no film that had enough mechanical strength to be used as a self-supporting film and in which layers of clay particles were highly oriented. Meanwhile, in the cosmetic and pharmaceutical fields, there have been proposals for a favorable spherical, organic, composite clay mineral (Japanese Laid-Open Patent Application S63-64913 and Japanese Patent Publication H07-17371), the manufacture of a drug for treating wet athlete's foot, comprising a mixture of a clay mineral, an acid, and an enzyme (Japanese Laid-Open Patent Application S52-15807 and Japanese Patent Publication S61-03767), and so forth in which clay and an organic compound were compounded. Nevertheless, it is a fact that these organic composite clay minerals have yet to be used as self-supporting films, and there is an urgent need in this field of technology for the development and practical application of a novel clay thin film having enough mechanical strength to be used as a self-supporting film.